1. Technical Field
The present invention relates to a printing apparatus for performing printing on a medium.
2. Related Art
A color printer, which is an example printing apparatus, including a transfer unit (printing unit) for transferring a toner image onto a sheet of paper, which is an example medium, is known (see, for example, JP-A-2014-38201). Such a color printer includes a registration roller pair (correction roller pair) that enables the leading edge of a sheet of paper to strike the registration roller pair to correct skewing of the sheet and transports the sheet toward the transfer unit.
If the pressing force of the registration roller pair is too weak (the pinching load is small, i.e., the nip load applied to the registration roller pair is small), the sheet can pass through the registration roller pair and the skewing is not corrected. On the other hand, if the pressing force of the registration roller pair is too strong, when the trailing edge of the sheet passes through the registration roller pair, the sheet transport speed changes undesirably. To address the problem, in the color printer, the pressing force of the registration roller pair is reduced after skewing of the sheet has been corrected.
In such a color printer (laser printer), the pressing force of the registration roller pair is reduced after the leading edge of the sheet has passed through the registration roller pair and before the trailing edge of the sheet passes through the registration roller pair.
Compared with the laser printer, an ink jet printer needs be more carefully designed to prevent transfer of ink onto a transport path, especially, transfer of ink onto a registration roller pair. Accordingly, it is preferable that the pressing force of the registration roller pair be changed at an appropriate time in consideration of skew correction and transfer prevention.